[Bug c/32536] New: wrong generated code on complex statement;

[gcc-bugzilla at gcc dot gnu dot org]

sample code:

#include <stdio.h>

int main()
{
  char cp[2];
  cp[0] = 'A';
  cp[1] = 'B';
  printf("%x %x\n",cp[0],cp[1]);
  cp[0] ^= (cp[1]^=(cp[0]^=cp[1]));
  printf("%x %x\n",cp[0],cp[1]);
  return 0;
}

The complex byte swapping instruction is far fetched but seems legal.
It actually swaps bytes if compiled with "gcc -O3". Without optimization, 
one of the bytes receives a '\0'. 
   This instruction seemed to work properly with versions 3.

Environment:
System: Linux lpnp204 2.4.21-47.0.1.EL.cernsmp #1 SMP Thu Oct 19 16:35:52 CEST
2006 i686 i686 i386 GNU/Linux
Architecture: i686


host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: ./configure

How-To-Repeat:
        Compile the code above with various degrees of optimization.


-- 
           Summary: wrong generated code on complex statement;
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: astier at lpnp204 dot in2p3 dot fr
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32536